My impression about performances recorded of this song,
is that Little Willie John
was the first to record it.
Then comes B. B. King,
whose arrangement was influential
to Peter Green's Fleetwood Mac, it sounds like.

What else?
Mertis John Sr. was the father
of Willie John and Mertis John Jr. who were two out of ten children.
Four of the older children sang together as The Gospel Four --
not clear if Mertis Jr. was one of those four.

Another quote I scared up:
"... his older brother, Mertis John Jr., who
penned material while serving in Korea as a medic."

There is supposed to be a Little Willie John biography
authored by Susan Whitall
which goes into some detail about
the two brothers and their families.